Thermal circuit interrupter



H. SIEBEN THERMAL CIRCUIT INTERRUPTER Filed Jan. 10, 1921 1 l N V E N T 01? B y flan/y 51am.

A TTORNE V Patented Dec. l5, l lzd.

" T T E S HENRY smart, or nansascrrn, mssonnr, Assicnor, 'ro cnnnnn's o. nonrnn, or nnnsns (CITY, mssonni.

THERMAL CIRCUIT INTERR'UPTER.

Application filed January. to, 1921. Serial No. scenes.

v To all whom it may concern:

Be it known that 1, Hanan Sinn'niv a citizen of the United States, residing at ansas City, in the county of Jackson'and State of Missouri, have invented certain new and useful Improvements in Thermal Circuit interrupters; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertainsto make and use the same, reference being had to the accompanying drawings, and to the letters and figures of reference marked thereon, which form a part of this specification.

This invention relates to automatic cutouts for electric circuits and the invention is particularly a plicable for interrupting a circuit connects to a heating element, for example, an electric iron, chafing dish, perculator, hot plate or the like.

If the circuit is not interrupted after the heating element, such as an electric iron or the like, has been heated beyond a safe temperature, there is grave liability of fire due to the fact that the support for the heating element may become ignited.

A great number of fires are causedv each year due to the fact that the electric iron carelessly left upon the ironing hoard or table with the current on operator has her attention directed to other inatters. In such an event, the iron soon becomes very hot and burns through the ironin}: board or table with disastrous results.

My invention contemplates electric circuit breaker or interrupter whici'i be actuated in response to a rise temperature of the iron or other element to which the device is attached and l preferably construct the device in the fiorm of a plug or connector so that it may be readily applied to existing types of electrically heated devices,

The invention is not to be actuated in response to a surge in current but it is to he operated in response to a rise in temperature of the heated device to which it is attached, and to this end l have provided a thermowil - statically controlled circuit breaker or interrupter which can be set so as to allow cur rent to enter the heating element or a device containing a heating element and which will remain set until the temperature of the device to which it is attached has risen bebeyond a determined value @no form of my invention is illustrated'in the accompanying drawings, in which-- Fig. 1 is a disassociated view of an electric iron and a plug therefor containing the essential features of the invention.

Fig.2 is a disassociated view of a contact block and a switch to co-operate therewith.

Fig. 3 is' a detail perspective view of a connector and hot point to cause actuation of the thermostat.

Fig. 4 is an elevational view of the switch.

Fig. 5,is a detail perspective view of the switch-carrying ratchet and the block supporting it.

Fig. 6 is a detail perspective view of a heat conducting plate and a motor for actuating' the switch in response to the thermostat, and

7 is a vertical, longitudinal, sectional view through a plug in which my invention is incorporated, the same being shown as attached to the rear end of an electric iron.

The iron 1 may he of standard construetion two upstanding pins 3 and i as is common with such devices. The plug is shown as consisting or" two blocks 5 and 6 of insulating; material, the blocks supporting the. switch and contact. A heat conducting plate Z is provided for conveying heat to a thermostat, the plate 7 in the pres ent embodiment of my invention also locing used as a support for the actuating motor or spring for throwing the switch at theproper time. The block 6 carries its lower end two socket contacts 8 and 9, which are adapted to fit overthe pins 4 and 3 on the iron 1. The contact 9 is provided with an offset projection 10, shown as diametrically opposite offset projection 11 of the complementary contact 12 on opposite sides of a central opening 13 in block 6 (see Fig. 2). The contact 12 is connected to the socket contact 8 by a connector 14, which has an integral disk or circular plate 15 bridging the opening 13 (Figs. 2 and 3).

The block 6 carries a pivoted switch rearding detent 16 shown as comprising an elbow lever having a lateral hooked arm 17 and a vertical notched arm 18, the latter constituting a detent for engaging a pin 19 on a dish 29, to which is fixed through a tusible material 21 a ratchet ring 2%, lying within the opening 13 and facing in the direction opposite to the contacts and detent it. The ratchet ring is adapted to be hell Nil against rotation in one direction by a springpressed pawl 23 in the recess 24 of the block 6 and on the side opposite to that which carries the contacts 8 and 9.

The disk has a rigid lateral pin or shaft 24 which proiects through the opening 25 in the disk or plate 15 and rotatably mounted upon the shaft 24 is a spring-actuated switch consisting of a disk 26 of insulating material and carrying a bridging contact 27 having yielding pairs of spring-arms 28 and 29 adapted to engage between them the contacts 10 ,and 11.

A coil spring 30 on the end of the shaft 24 has one'end abutting against a pin 31 on the shaft 24 and the other end engaging the disk so that there will be a tendency to swing the disk 26 in one direction. The swinging movement of the disk, however, will be opposed by the outstanding pin 19 which is adapted to engage a shoul er 32 on the disk 26. There is a detent-engaging tooth 33 on the disk 26 which is adapted to be engaged by the notches on the arm 18, when the disk 26 is initially'rotated to snap the switch into circuit closing position, the detent being held into en by a spring 34 and said etent is movable out of en gement with the tooth 33 by the pin 19, w ich may ride against it, as will be presently described.

Rotatably mounted in the heat conductor plate 7 is a disk 36, which carries a knob 37, rigidly connected to said disk and within which is a spring 38 coiled about the shaft 39, one end engagin the shaft and the other the plate 7 so that t e spring, knob and disk constitute a motor for throwing the switch when the thermostat shown as the fusible element 21 has been melted. The disk 36 carries a pin which is adapted to contact with a complementary pin 41 on the disk 20 to turn the disk when the fusible element 21 has been melted or fused by the heatpussingfrom the iron 1 throu h a spring contact 42, and plate 7 to the Ersible element 21 or through the pins 3 and 4, contact 8, connector 14 and hot point or plate 15.

When the parts are assembled and in their normal positions with the blocks 5 and 6 and late 7 in place. the disks 20 and 36 will 9 secured together through the medium of the material 21 which at that time. will be solidified.v The knurled knob 37 may be turned in a clockwise direction to turn the disk 20 in a clockwise direction. During ent with 33 in -a contra-clockwise direction when viewed from the opposite side of the plate.-

lVhen the initial turning movement heins, the switch contacts 28 and 29 will be in subdantially lateral ositions and the plate 26 and plate 20 will rotate ther because pin 19 will lie against shoul er 32 until the tooth 33 is engaged by the hook 43 on the detent arm 18. The turning movement of the disk 26 will then be arrested while the disk 20 continues to rotate storing up energy in the spring 31 until the pin 19 contacts with one of the shoulders 44 on the detent arm 18 to move the hook 43 out of engagement with the tooth 33, whereupon the spring tension, stored up by winding the spring 31 while hook 43 engaged tooth 33 will snap the switch contacts 28 and 29 into contact with 10 and 11. The circuit is now made and current may pass from the conductor through contact 12, across the switdito contact 10, through contact '9, through pinthrough the heating element in the iron 1. through pin 4, contact 8 connector 14 and contact 12 back to the source of current supply.

The turning of the knob 37 to set the switch will store up energy in the motor consisting of the spring 38. the knob 37 and the disk '36 so there will be a tendency to swing the disk '20 in a contra-clockwise direction due to the stored energy in the spring 38 and knob '37. The rotative action cannot tak place, however. because the disk 20 and disk 36 will be soldered together by the fusible material 21 and the rotative movement of the disk 20 will be opposed by the ratchet ring rigid therewith and the pawl 23. When, however, the heat of the heated device. for example an iron, is raised to a determined degree in temperature. the conducted heat through pin 4, contact 8. connector 14 and plate or disk 15 will fuse the material 21, allowing the spring 38 to rotate the shaft 39, the plate 36, the disk 20. the disk 26 and the switch about to break contact with contacts 10 and 11. Therefore. the circuit will be interrupted and the heated device will be permitted to cool.

The interrupting of the circuit will be caused by the fusing of the material 21, which will release the disk 20 from the ratchet ring 22. the disk 20 also being released from the disk 36 when the material 21 is fused so that the disks 20 and 36 and the ratchet 22'are all disconnected. The spring 38 will then be permitted to uncoil. rotating the disk 36 so that the pin 40 will strike against the pin 41 on the disk 20 and. during the rotation of the disk 36, cause the disk 20 to rotate in a reverse direction so as to move it out of contact with the electrical terminal contacts 10 and 11 until contacts 28 and 29 on the switch will have moved through an arc of about 90 or, in

' porarily hold other words, assumed. horizontal positions instead of vertical positions. The switch cannot now be re-set untilthe material 2-1 has solidified, connecting up the disks 20 and 36 and the ratchet ring 22 because of the stop pins 45 and 45' between which pin 46 lays if the knob 37 is turned, the disk 36 Wil rotate without effecting a rotative movement to the disk 20. This is a safety feature, preventing the operator from resetting the switch and maintaining a high heat in the iron or other device to which the circuit breaker is attached.

It will follow, therefore, that when the material 21 has been fused, the iron must cool or at least, the fusible material 21 must cool and solidify before the circuit can again be closed.

The plate 7 is provided with stop pins 45 and 45', between which the pin 46 on knob 37 moves; therefore, the rotative movement of the knob 37 vwill be limited by the stop pins 45 and 45'. I

A concavo-convex spring disk 47, which bears against the end of the shaft 24' will act as a friction plate to'hold the parts in proper co-operative relation.

Attention is called to the fact that the spring contact 42 will possess enough yieldability and flexibility to cause it to rest against the heels of irons of different formations. Some irons are formed with their heels provided with substantially vertical ends, others are inclined to a more or less extent, and since the plug circuit breaker is intended to be applicable to universal use, it is important that perfect heat conductivity contact be made with the heel of the iron to which the plug is attached. Therefore, the spring 42 becomes an important adjunct of the invention.

What I claim and desire to secure by Letters-Patent is:

1. In a device of the class described, a pair of electric contacts, a switch for bridging the contacts, a rotatable element comprising two members in line with the axis of the switch, a fusible connection between the two members, a detent, a spring for putting the switch under tension, means on the switch for engagement with the detent to temit stationary while the rotatable element turns so that the spring will be put under tension, and means for releasing the switch to permit it to snap into circuit closing position under tension of the spring after the rotatable element has moved through a determined arc.

2. A device of the class described comprising a rotatable shaft, a switch loosely mounted on said shaft, a rotatable element in line with said shaft comprising two members, a fusible element between the members, a spring against which the rotatable element may be manually wound, when the two members are connected, a detent for holding the switch against movement during a partial rotation of the rotatable element and releasable after the rotatable element has moved through a determined arc whereby the switch may be snapped into circuit closing position under tension of the spring, and means for causing the spring on the r0- tatable element to reverse the movement of the rotatable element when the fusible element softens.

3. In a device of the class described, a

disk. a ratchet ring, fusible material connecting the ring to said disk, a pawl for engagement with the ratchet ring, a switch on the disk, a rotatable element comprising a spring-pressed shaft having a diskfusible material connecting the first and second mentioned disks, a detent adapted to temporarily retard the switch during a partial rotation of the rotatable element and to release it when the rotatable element has moved through a determined arc, and means between the two disks for co-operative engagement upon reversal of movement of the rotatable element and upon fusing of thematerials for connecting the first named disk and the ratchet and the two disks together. 4. In a device of the class described, a

shaft, a spring-actuated switch on said shaft, a disk carried by said shaft, a ratchet ring, a fusible material between the ratchet ring and disk, a pawl for engagement with the ratchet, a pin projecting from said disk, a disk in line therewith, a pin on the second mentioned disk adapted to contact with the pin on the first named disk. a spring-actuated shaft rigidly connected to the second mentioned disk, and means for tensioning the spring for the switch and releasing it during the rotation of the rotatable element in one direction.

5. In a device of the class described, a plug having spaced contacts, a thermostatically controlled switch in the plug for bridging the contacts, the switch including a fusible element, a heat conductor carried by the plug, and a hotpoint plate having its greatest point of heat radiationadjacent to the fusible element of the switch.

In testimony whereof I affix my signature.

HENRY SIEBEN. 

